Manufacture of artificial threads



Patented Aug. 27, 1940 UNITED STATES MANUFACTURE or ARTIFICIAL THREADS PATENT OFFICE Walter Maier, J essnitz, Anhalt, and Gaston Plepp and Heinrich Fink, Wolfen, Kreis Bitterfeld, Germany, assignors to I. G. Farbenindustrie Aktiengesellschaft, Frankfort on the Main,

Germany 6 Claims.

Our invention relates to the manufacture of artificial threads and more particularly to artificial threads containing sulfur and nitrogen.

One of its objects is a process of producing artificial threads from viscose containing sulfur and nitrogen. Further objects will be seen from the detailed specification following hereafter.

In U. S. Patent No. 2,122,801, the inventor of which is a co-inventor of the present application a process has been described according to which solutions of cellulose xanthateare spun to xanthate fibers by using a coagulating bath whereafter said fibers were reacted with cyclic ethylene imines to form derivatives of thiazolidine while preserving the structure of the fiber. The process is carried out with spinning baths containing salt and at most 4.2 per cent of sulfuric acid, that is to say the conditions are such that any noteworthy elimination of xanthate groups from the freshly coagulated fiber is avoided before the reaction with the cyclic imine. However, spinning baths with such a low content of acid are only rarely used in modern viscose spinning processes.

The present invention is based on the observation that fibers with a sufficient content of nitrogen and sulfur can also be obtained when using spinning baths containing considerably more than 4 per cent of sulfuric acid. It has been found that not only the ordinary Mueller-baths, but also the baths used for the production of fibers of high tenacity give good results. The baths may contain 5 to 100 per cent of acid. By this invention it has become possible to apply the above process which has hitherto been restricted to certain spinning baths to every viscose spinning process. The spinning baths may contain inorganic or organic acids or mixtures of both in concentrations of a few per cent up to pure acid. The baths may comprise water, alcohols or other organic sOlvents. Moreover there may be present salts with monoor polyvalent cations, for instance they may be wholly or partly saturated with sodium sulfate, magnesium sulfate, zinc-sulfate or mixtures thereof. Furthermore the spinning baths may contain other additions, for instance products of condensation of aldehydes with aromatic sulfonic acids, wetting agents, etc. The process is not limited to a special temperature; the spinning baths may for instance be kept without disadvantage at 80 C. or they may have a still higher temperature.

As it has been pointed out in the above named Patent No. 2,122,801 the ethylene imine may be applied in solutions or in the form of vapor while the solution of the base may be wholly or partly neutralized. If it is desired the ethylene imine may also be added to the acid spinning baths. However this way of carrying out the process can only be recommended for special cases, since it is not very economical. In the presence of free ethyleneimine bases more than 1 mol of ethylene imine is bound by one xanthate group. The con- 'centration and the time of reaction of the ethylene imine solution may be adjusted in such a way that all or only part of the xanthate groups present in the coagulated fibers are brought to reaction with the ethylene imine. In each case it is of advantage after the ethylene imine has reacted to take care by a short heating to complete the reaction. The success of the spinning process is dependent upon the concentration of the spinning acid, the temperature of the spinning bath and the length of the precipitating bath or on the interval between the precipitating bath and the reaction vessel respectively which must be adjusted in such a way that the fiber bundle which is to be reacted with the cyclic imines contains such an amount of xanthate groups that the fiber in the dried condition contains sufficient nitrogen so that it may be dyed with wool dyestuffs. It is surprising that this result is obtained even with the strongest acid baths and without the application of especially highly sulfidized viscose by very simple means. For instance the length of the precipitating bath may be shortened, a washing bath which may consist of hot water or of a salt solution may be used after the spinning bath. Longer air intervals between the spinning bath and the reaction vessel in which the fiber is treated with the ethylene imine must be avoided. This process is of great practical importance for the reason that it may be used in ordinary spinning processes without necessitating considerable changes.

The fibers spun according to this process distinguish from those obtained according to the above identified application by an increased tenacity. These fibers have at least the same properties as regards the tenacity and extension as those obtatined by a corresponding spinning process in which the treatment with ethylene imine has not been intercalated. In some cases the fiber containing nitrogen has even better properties than those which are free from nitrogen. The fibers may be dyed, in admixture with wool, with wool-dyestuffs in the same degree of fastness and in the same tint.

The following examples serve to illustrate the invention:

(l) Viscose having a content of 55 xanthate groups per 100 cellulose Cs mols is spun in a spinning bath at 70 C. which contains 30 per cent of sodium sulfate and per cent of sulfuric acid, the length of immersion in the liquid being 12 cm. and the draught 60 meters per minute. The thread spun is 3.7 deniers. After a short passage through air the bundle of fibers is run through a water-bath at 50 C. and is drawn therefrom by means of galettes or squeezing rollers. Finally the bundle of fibers passes through a bath consisting of an aqueous ethylene-imine solution of 15 per cent strength and at C., whereupon the bundle, saturated with this solution, enters a hot chest in which it is kept for 20 seconds at 60 C. From here the bundle is acidified by the known method, desulfurized, brightened and dried. The fibers contain 2 per cent of nitrogen and 5 per cent of sulfur both in chemical combination and have the same affinity for W001 dyestuffs as wool has. Moreover the fibers have a deep, matt appearance.

(2) Viscose with 35 xanthate groups per 100 cellulose C6 mols is spun in a bath which contains '5 per cent of sulfuric acid and 36 per cent of ammonium sulfate and at a temperature of 45 C., the length of immersion being 20 cm. and the draught 50 in. per minute. The titre is fixed at 3.5 deniers. After travelling through cm. of air a bundle of fibers is drawn by squeezing rollers and then falls freely into a bath heated at 50 C. of aqueous ethylene-imine solution of 10 per cent strength wherein it remains for 30 seconds. ter the usual finishing the fiber contains 3 per cent of N and 9 per cent of S.

(3) Fresh viscose from unripened all-:ali cellulose containing 60 xanthate groups per 100 cellulose Cc mols is spun in a bath at 15 C. containing 17 per cent of sodium sulfate, 17 per cent of sulfuric acid and 2 per cent of carbon in the form of the condensation product from formaldehyde and naphthalene sulfuric acid ester, the length of immersion being 25 cm. and the speed of draught 50 in. per minute. The single titre produced is 2.4 deniers. Finally the bundle passes through a bath of sodium sulfate solution of 20 per cent strength and at C.; thence it is drawn by means of a galette and falls freely into a solution at 42 C. which contains per liter 100 cc. of ethylene-imine and 60 cc. of glacial acetic acid. The reaction is complete after 20 seconds whereupon the bundle of fibers is finished by known methods. The fiber contains 2 per cent of N and 5 er cent of S.

(4) A viscose made from ripened alkali cellulose and containing 7.5 per cent of cellulose there being 54 xanthate groups per 100 C6 units is spun at 15 C. in a bath which has been made by esterifying 4 parts by weight of sulfuric acid of 96 per cent strength with one part of methanol. The length of immersion is 10 cm. and the draught 50 in. per minute. The titre fixed is 3.5 deniers. Behind the spinning bath the thread is stretched over several glass rods; then it passes through a water bath and after several meters passage through air is led over a reel into a bath at C. containing 10 per cent of ethyleneimine semi-neutralized with acetic acid. The bundle is in contact with this bath for one minute and is then washed and further treated in known manner. A fiber is obtained containing 1.5 per cent of nitrogen and 1.8 per cent of sulfur.

(5) The same viscose as is prescribed for use in Example 4 is spun at the same degree of ripeness in an aqueous solution containing '74 per cent of sulfuric acid at a draught of meters per minute and at a bath temperature of -4= C. The titre is fixed at 2 deniers. The immersion in the bath amounts to 10 cm. Over the spinning bath the thread is six times angularly deflected over thin glass rods whereupon it passes through a length of water of 30 cm. and after passage through some meters of air over a reel sprinkled with water into an ethyleneimine bath of the same composition and temperature as that prescribed in Example 4; it is withdrawn from this bath after one minute and further treated in known manner. The finished thread contains 0.7 per cent of nitrogen and 0.8 per cent of sulfur.

(6) The same viscose as that prescribed in Examples 4 and 5 is spun at a ripeness of 50 xanthate groups per 100 C6 units in a bath heated to 35 C. and containing 54.8 per cent of sulfuric acid and 15.7 per cent of ammonium sulfate and 4 per cent of sodium sulfate. The draught amounts to 50 meters per minute and the titre is fixed at 2.3 deniers. The length of immersion in the bath is 8 cm. and after leaving the bath the threads are stretched over three glass rods and then passed through 30 cm. of water bath whereupon after passing through 3 meters of air they enter the ethylene-imine of the same temperature and composition as prescribed in Examples 4 and 5. They remain in this bath for one minute. The finished threads contain 0.85 per cent of nitrogen and 0.9 per cent of sulfur.

What we claim is:

1. A process of producing artificial threads containing nitrogen and sulfur which comprises spinning viscose into a precipitating bath containing 5 to 100 per cent of acid, the acid content and the temperature of said spinning bath, the length of bath travel of said threads and the length of air travel as well as the speed of draught being so adjusted that the freshly spun threads still contain a substantial amount of cellulose xanthate, and reacting on said freshly spun threads with a cyclic ethylene imine.

2. A process of producing artificial threads containing nitrogen and sulfur which comprises spinning viscose into a precipitating bath con taining 5 to 100 per cent of sulfuric acid, the acid content and the temperature of said spinning bath, the length of bath travel of said threads and the length of air travel as well as the speed of draught being so adjusted that the freshly spun threads still contain a substantial amount of cellulose xanthate, and reacting on said freshly spun threads with a cyclic ethylene imine.

3. A continuous process of producing artificial threads containing nitrogen and sulfur which comprises spinning a viscose containing about 55 xanthate groups per 100 Cs molecules of cellulose into a precipitating bath containing 30 per cent of sodium sulfate and 15 per cent of sulfuric acid at a temperature of 70 C. with an immersion length of 12 cm. and at a speed of draught of meters per minute, to produce a bundle of xanthate threads, washing the bundle of threads in a water-bath of 50 C., continuously passing the bundle of threads through a bath consisting of an aqueous ethylene imine solution of 15 per cent strength of 20 C. and guiding the bundle of threads through a chamber heated at 60 C. to remain in said chamber for about 15 seconds.

4. A continuous process of producing artificial threads containing nitrogen and sulfur which comprises spinning a viscose containing 60 Xanthate groups per 100 C6 molecules of cellulose into a precipitating bath containing 17 per cent of sodium sulfate, 17 per cent of sulfuric acid and 2 per cent of carbon in the form of the condensation product from formaldehyde and naphthalene sulfuric acid at a temperature of 15 C. with an immersion length of 25 cm. and at a speed of draught of meters per minute, washing the coagulated threads in a bath consisting.

of an aqueous sodium sulfate solution of 20 per cent strength at a temperature of 35 0, continuously passing the bundle of threads through a bath of 42 C. containing 100 cc. of ethyleneimine and cc. of glacial acetic acid per liter and removing the threads from the bath after 20 seconds.

5. A process of producing artificial threads containing nitrogen and sulfur which comprises spinning a viscose solution containing 7.5 per cent of cellulose and 54 xanthate groups per Cs molecules of cellulose into a precipitating bath which has been made by esterifying 4 parts by weight of sulfuric acid and 96 per cent strength with one part of methanol at a temperature of 15 C. with an immersion length of 10 cm. and a speed of draught of 50 meters per minute, stretching the thread over several glass rods, passing the thread through a water-bath and after several meters passage through the air guiding the threads into a bath at 40 C. containing 10 per cent of ethylene-imine semi-neutralized with acetic acid to remain in said bath for 1 minute.

6. A process of producing artificial threads containing nitrogen and sulfur, which comprises spinning viscose into a precipitating bath containing 5 to 100 per cent of acid, the acid content and the temperature of said spinning bath, the length of bath travel of said threads and the length of air travel as well as the speed of draught being so adjusted that the freshly spun threads still contain a substantial amount of cellulose xanthate, leading said threads: into a neutral intermediate bath, and reacting on said freshly spun threads with a cyclic ethyleneimine.

WALTER MAIER. GASTON PLEPP. HEINRICH FINK. 

